2015-03-31 I&S Committee - Item 5 - Attachment 1 - Munna Pt Bridge Repairs Level 3 Bridge Report

o   Pilecap Beams
    • Carbonation was at safe levels (0 to 14mm penetration, so nowhere near
        reinforcement).
    • Chlorides in the supposedly better pilecaps (Piers 1, 2 & 6) varied: in pilecaps of
        Piers 1 & 6, the chlorides were below corrosion threshold at the reinforcement
        depth, which is consistent with the smaller amount of cracks observed. In the
        pilecap of Pier 2, chlorides exceed the corrosion threshold at the reinforcement
        depth of 89mm to 100mm.
    • Crack depths were 12 to 198mm deep on the top of pilecap beam (Pier 4),
        according to survey using ultrasonic pulse velocity device.

o   Piles
    • Chlorides were (unsurprisingly) found to be well over the corrosion threshold in
        Pile 1 (Pier 1). However, it should be noted that it was very difficult to take a test
        sample on site because even at extreme low tide, the top of the pile was still
        getting wet from waves, and its likely that saltwater intrusion made the results
        artificially high. ALS Industrial notes although the piles are primarily in a
        submerged condition and this restrictive of oxygen ingress, they are in a
        substantively compromised position with regard to corrosive stability.

2.2 Tod Site Investigation Photos




Photo A – Pier 1, small cracks at bottom of pilecap     Photo B – Pier 2, small cracks at top of pilecap beam
beam




                                                 Page 17 of 31